The invention relates generally to hydraulic valves.
Of particular interest to the invention is a hydraulic valve of the type having a spool mounted for longitudinal movement in a housing or valve body. The valve body is provided with a fluid inlet chamber, at least one user chamber which is arranged for communication with a user of the fluid and (at least one return or reflux chamber for recovering fluid from the user. Depending upon its position, the spool permits the user chamber to communicate with the fluid inlet chamber while sealing the user chamber from the return chamber or permits the user chamber to communicate with the return chamber while sealing the user chamber from the fluid inlet chamber. The valve body is further provided with a flow channel which is arranged for communication with a source of fluid and opens to a pair of sides or flange faces of the valve body. The flow channel is arranged so that it may communicate with the fluid inlet chamber and a check valve is provided for sealing the fluid inlet chamber from the flow channel. The check valve includes a sealing member which is biased towards a closed position, that is, a position in which the fluid inlet chamber is sealed from the flow channel, by a spring.
In a known hydraulic valve of this type having a pair of user chambers, the check valve is arranged so that its axis extends parallel to the flow channel connecting the sides of the valve body. The sealing member of the check valve, together with a spring, is inserted into a blind bore from a flange face or side of the valve body. This construction requires a relatively large amount of space for the check valve, which latter also serves to seal the two user chambers from the flow channel. Such a large amount of space is hardly available in hydraulic valves, particularly in hydraulic valves having a block-like configuration. For a valve body of given size, the space required for a check valve which is constructed as described above results in decreased flow cross-sections and, consequently, in an increased resistance to flow. Moreover, the many changes in flow direction which are a result of the check valve construction described above lead to a further increase in the resistance to flow. In addition, by virtue of the above-outlined arrangement of the check valve, the known hydraulic valve of the type under consideration is expensive to manufacture and is not well-suited for the incorporation of additional valve elements in the same valve body.